package org.g4studio.core.mvc.xstruts.util;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.io.Serializable;

import java.text.MessageFormat;

import java.util.HashMap;
import java.util.Locale;

/**
 * General purpose abstract class that describes an API for retrieving
 * Locale-sensitive messages from underlying resource locations of an
 * unspecified design, and optionally utilizing the <code>MessageFormat</code>
 * class to produce internationalized messages with parametric replacement.
 * <p>
 * Calls to <code>getMessage()</code> variants without a <code>Locale</code>
 * argument are presumed to be requesting a message string in the default
 * <code>Locale</code> for this JVM.
 * <p>
 * Calls to <code>getMessage()</code> with an unknown key, or an unknown
 * <code>Locale</code> will return <code>null</code> if the
 * <code>returnNull</code> property is set to <code>true</code>. Otherwise, a
 * suitable error message will be returned instead.
 * <p>
 * <strong>IMPLEMENTATION NOTE</strong> - Classes that extend this class must be
 * Serializable so that instances may be used in distributable application
 * server environments.
 * 
 * @version $Rev: 421119 $ $Date: 2005-08-29 23:57:50 -0400 (Mon, 29 Aug 2005) $
 */
public abstract class MessageResources implements Serializable {
	// ------------------------------------------------------------- Properties

	/**
	 * Commons Logging instance.
	 */
	protected static Log log = LogFactory.getLog(MessageResources.class);

	// --------------------------------------------------------- Static Methods

	/**
	 * The default MessageResourcesFactory used to create MessageResources
	 * instances.
	 */
	protected static MessageResourcesFactory defaultFactory = null;

	/**
	 * The configuration parameter used to initialize this MessageResources.
	 */
	protected String config = null;

	/**
	 * The default Locale for our environment.
	 */
	protected Locale defaultLocale = Locale.getDefault();

	/**
	 * The <code>MessageResourcesFactory</code> that created this instance.
	 */
	protected MessageResourcesFactory factory = null;

	/**
	 * The set of previously created MessageFormat objects, keyed by the key
	 * computed in <code>messageKey()</code>.
	 */
	protected HashMap formats = new HashMap();

	/**
	 * Indicate is a <code>null</code> is returned instead of an error message
	 * string when an unknown Locale or key is requested.
	 */
	protected boolean returnNull = false;

	/**
	 * Indicates whether 'escape processing' should be performed on the error
	 * message string.
	 */
	private boolean escape = true;

	// ----------------------------------------------------------- Constructors

	/**
	 * Construct a new MessageResources according to the specified parameters.
	 * 
	 * @param factory
	 *            The MessageResourcesFactory that created us
	 * @param config
	 *            The configuration parameter for this MessageResources
	 */
	public MessageResources(MessageResourcesFactory factory, String config) {
		this(factory, config, false);
	}

	/**
	 * Construct a new MessageResources according to the specified parameters.
	 * 
	 * @param factory
	 *            The MessageResourcesFactory that created us
	 * @param config
	 *            The configuration parameter for this MessageResources
	 * @param returnNull
	 *            The returnNull property we should initialize with
	 */
	public MessageResources(MessageResourcesFactory factory, String config, boolean returnNull) {
		super();
		this.factory = factory;
		this.config = config;
		this.returnNull = returnNull;
	}

	/**
	 * The configuration parameter used to initialize this MessageResources.
	 * 
	 * @return parameter used to initialize this MessageResources
	 */
	public String getConfig() {
		return (this.config);
	}

	/**
	 * The <code>MessageResourcesFactory</code> that created this instance.
	 * 
	 * @return <code>MessageResourcesFactory</code> that created instance
	 */
	public MessageResourcesFactory getFactory() {
		return (this.factory);
	}

	/**
	 * Indicates that a <code>null</code> is returned instead of an error
	 * message string if an unknown Locale or key is requested.
	 * 
	 * @return true if null is returned if unknown key or locale is requested
	 */
	public boolean getReturnNull() {
		return (this.returnNull);
	}

	/**
	 * Indicates that a <code>null</code> is returned instead of an error
	 * message string if an unknown Locale or key is requested.
	 * 
	 * @param returnNull
	 *            true Indicates that a <code>null</code> is returned if an
	 *            unknown Locale or key is requested.
	 */
	public void setReturnNull(boolean returnNull) {
		this.returnNull = returnNull;
	}

	/**
	 * Indicates whether 'escape processing' should be performed on the error
	 * message string.
	 * 
	 * @since Struts 1.2.8
	 */
	public boolean isEscape() {
		return escape;
	}

	/**
	 * Set whether 'escape processing' should be performed on the error message
	 * string.
	 * 
	 * @since Struts 1.2.8
	 */
	public void setEscape(boolean escape) {
		this.escape = escape;
	}

	// --------------------------------------------------------- Public Methods

	/**
	 * Returns a text message for the specified key, for the default Locale.
	 * 
	 * @param key
	 *            The message key to look up
	 */
	public String getMessage(String key) {
		return this.getMessage((Locale) null, key, null);
	}

	/**
	 * Returns a text message after parametric replacement of the specified
	 * parameter placeholders.
	 * 
	 * @param key
	 *            The message key to look up
	 * @param args
	 *            An array of replacement parameters for placeholders
	 */
	public String getMessage(String key, Object[] args) {
		return this.getMessage((Locale) null, key, args);
	}

	/**
	 * Returns a text message after parametric replacement of the specified
	 * parameter placeholders.
	 * 
	 * @param key
	 *            The message key to look up
	 * @param arg0
	 *            The replacement for placeholder {0} in the message
	 */
	public String getMessage(String key, Object arg0) {
		return this.getMessage((Locale) null, key, arg0);
	}

	/**
	 * Returns a text message after parametric replacement of the specified
	 * parameter placeholders.
	 * 
	 * @param key
	 *            The message key to look up
	 * @param arg0
	 *            The replacement for placeholder {0} in the message
	 * @param arg1
	 *            The replacement for placeholder {1} in the message
	 */
	public String getMessage(String key, Object arg0, Object arg1) {
		return this.getMessage((Locale) null, key, arg0, arg1);
	}

	/**
	 * Returns a text message after parametric replacement of the specified
	 * parameter placeholders.
	 * 
	 * @param key
	 *            The message key to look up
	 * @param arg0
	 *            The replacement for placeholder {0} in the message
	 * @param arg1
	 *            The replacement for placeholder {1} in the message
	 * @param arg2
	 *            The replacement for placeholder {2} in the message
	 */
	public String getMessage(String key, Object arg0, Object arg1, Object arg2) {
		return this.getMessage((Locale) null, key, arg0, arg1, arg2);
	}

	/**
	 * Returns a text message after parametric replacement of the specified
	 * parameter placeholders.
	 * 
	 * @param key
	 *            The message key to look up
	 * @param arg0
	 *            The replacement for placeholder {0} in the message
	 * @param arg1
	 *            The replacement for placeholder {1} in the message
	 * @param arg2
	 *            The replacement for placeholder {2} in the message
	 * @param arg3
	 *            The replacement for placeholder {3} in the message
	 */
	public String getMessage(String key, Object arg0, Object arg1, Object arg2, Object arg3) {
		return this.getMessage((Locale) null, key, arg0, arg1, arg2, arg3);
	}

	/**
	 * Returns a text message for the specified key, for the default Locale. A
	 * null string result will be returned by this method if no relevant message
	 * resource is found for this key or Locale, if the <code>returnNull</code>
	 * property is set. Otherwise, an appropriate error message will be
	 * returned.
	 * <p>
	 * This method must be implemented by a concrete subclass.
	 * 
	 * @param locale
	 *            The requested message Locale, or <code>null</code> for the
	 *            system default Locale
	 * @param key
	 *            The message key to look up
	 */
	public abstract String getMessage(Locale locale, String key);

	/**
	 * Returns a text message after parametric replacement of the specified
	 * parameter placeholders. A null string result will be returned by this
	 * method if no resource bundle has been configured.
	 * 
	 * @param locale
	 *            The requested message Locale, or <code>null</code> for the
	 *            system default Locale
	 * @param key
	 *            The message key to look up
	 * @param args
	 *            An array of replacement parameters for placeholders
	 */
	public String getMessage(Locale locale, String key, Object[] args) {
		// Cache MessageFormat instances as they are accessed
		if (locale == null) {
			locale = defaultLocale;
		}

		MessageFormat format = null;
		String formatKey = messageKey(locale, key);

		synchronized (formats) {
			format = (MessageFormat) formats.get(formatKey);

			if (format == null) {
				String formatString = getMessage(locale, key);

				if (formatString == null) {
					return returnNull ? null : ("???" + formatKey + "???");
				}

				format = new MessageFormat(escape(formatString));
				format.setLocale(locale);
				formats.put(formatKey, format);
			}
		}

		return format.format(args);
	}

	/**
	 * Returns a text message after parametric replacement of the specified
	 * parameter placeholders. A null string result will never be returned by
	 * this method.
	 * 
	 * @param locale
	 *            The requested message Locale, or <code>null</code> for the
	 *            system default Locale
	 * @param key
	 *            The message key to look up
	 * @param arg0
	 *            The replacement for placeholder {0} in the message
	 */
	public String getMessage(Locale locale, String key, Object arg0) {
		return this.getMessage(locale, key, new Object[] { arg0 });
	}

	/**
	 * Returns a text message after parametric replacement of the specified
	 * parameter placeholders. A null string result will never be returned by
	 * this method.
	 * 
	 * @param locale
	 *            The requested message Locale, or <code>null</code> for the
	 *            system default Locale
	 * @param key
	 *            The message key to look up
	 * @param arg0
	 *            The replacement for placeholder {0} in the message
	 * @param arg1
	 *            The replacement for placeholder {1} in the message
	 */
	public String getMessage(Locale locale, String key, Object arg0, Object arg1) {
		return this.getMessage(locale, key, new Object[] { arg0, arg1 });
	}

	/**
	 * Returns a text message after parametric replacement of the specified
	 * parameter placeholders. A null string result will never be returned by
	 * this method.
	 * 
	 * @param locale
	 *            The requested message Locale, or <code>null</code> for the
	 *            system default Locale
	 * @param key
	 *            The message key to look up
	 * @param arg0
	 *            The replacement for placeholder {0} in the message
	 * @param arg1
	 *            The replacement for placeholder {1} in the message
	 * @param arg2
	 *            The replacement for placeholder {2} in the message
	 */
	public String getMessage(Locale locale, String key, Object arg0, Object arg1, Object arg2) {
		return this.getMessage(locale, key, new Object[] { arg0, arg1, arg2 });
	}

	/**
	 * Returns a text message after parametric replacement of the specified
	 * parameter placeholders. A null string result will never be returned by
	 * this method.
	 * 
	 * @param locale
	 *            The requested message Locale, or <code>null</code> for the
	 *            system default Locale
	 * @param key
	 *            The message key to look up
	 * @param arg0
	 *            The replacement for placeholder {0} in the message
	 * @param arg1
	 *            The replacement for placeholder {1} in the message
	 * @param arg2
	 *            The replacement for placeholder {2} in the message
	 * @param arg3
	 *            The replacement for placeholder {3} in the message
	 */
	public String getMessage(Locale locale, String key, Object arg0, Object arg1, Object arg2, Object arg3) {
		return this.getMessage(locale, key, new Object[] { arg0, arg1, arg2, arg3 });
	}

	/**
	 * Return <code>true</code> if there is a defined message for the specified
	 * key in the system default locale.
	 * 
	 * @param key
	 *            The message key to look up
	 */
	public boolean isPresent(String key) {
		return this.isPresent(null, key);
	}

	/**
	 * Return <code>true</code> if there is a defined message for the specified
	 * key in the specified Locale.
	 * 
	 * @param locale
	 *            The requested message Locale, or <code>null</code> for the
	 *            system default Locale
	 * @param key
	 *            The message key to look up
	 */
	public boolean isPresent(Locale locale, String key) {
		String message = getMessage(locale, key);

		if (message == null) {
			return false;
		} else if (message.startsWith("???") && message.endsWith("???")) {
			return false; // FIXME - Only valid for default implementation
		} else {
			return true;
		}
	}

	// ------------------------------------------------------ Protected Methods

	/**
	 * Escape any single quote characters that are included in the specified
	 * message string.
	 * 
	 * @param string
	 *            The string to be escaped
	 */
	protected String escape(String string) {
		if (!isEscape()) {
			return string;
		}

		if ((string == null) || (string.indexOf('\'') < 0)) {
			return string;
		}

		int n = string.length();
		StringBuffer sb = new StringBuffer(n);

		for (int i = 0; i < n; i++) {
			char ch = string.charAt(i);

			if (ch == '\'') {
				sb.append('\'');
			}

			sb.append(ch);
		}

		return sb.toString();
	}

	/**
	 * Compute and return a key to be used in caching information by a Locale.
	 * <strong>NOTE</strong> - The locale key for the default Locale in our
	 * environment is a zero length String.
	 * 
	 * @param locale
	 *            The locale for which a key is desired
	 */
	protected String localeKey(Locale locale) {
		return (locale == null) ? "" : locale.toString();
	}

	/**
	 * Compute and return a key to be used in caching information by Locale and
	 * message key.
	 * 
	 * @param locale
	 *            The Locale for which this format key is calculated
	 * @param key
	 *            The message key for which this format key is calculated
	 */
	protected String messageKey(Locale locale, String key) {
		return (localeKey(locale) + "." + key);
	}

	/**
	 * Compute and return a key to be used in caching information by locale key
	 * and message key.
	 * 
	 * @param localeKey
	 *            The locale key for which this cache key is calculated
	 * @param key
	 *            The message key for which this cache key is calculated
	 */
	protected String messageKey(String localeKey, String key) {
		return (localeKey + "." + key);
	}

	/**
	 * Create and return an instance of <code>MessageResources</code> for the
	 * created by the default <code>MessageResourcesFactory</code>.
	 * 
	 * @param config
	 *            Configuration parameter for this message bundle.
	 */
	public synchronized static MessageResources getMessageResources(String config) {
		if (defaultFactory == null) {
			defaultFactory = MessageResourcesFactory.createFactory();
		}

		return defaultFactory.createResources(config);
	}

	/**
	 * Log a message to the Writer that has been configured for our use.
	 * 
	 * @param message
	 *            The message to be logged
	 */
	public void log(String message) {
		log.debug(message);
	}

	/**
	 * Log a message and exception to the Writer that has been configured for
	 * our use.
	 * 
	 * @param message
	 *            The message to be logged
	 * @param throwable
	 *            The exception to be logged
	 */
	public void log(String message, Throwable throwable) {
		log.debug(message, throwable);
	}
}
